From the Magazine

A boom in boomless seismology

Taking advantage of cheap, long-lasting sensors developed by the oil and gas industry, seismologists are increasingly exploring the top 10 kilometers of the crust with dense surveys of hundreds or even thousands of seismometers. What's more, the surveys are being operated passively, which means that ambient noise from Earth is used to illuminate the subsurface. Passive surveys are cheaper and easier to permit than active surveys, which rely on explosives or vibrations from special "thumper trucks." Seismologists predict that the dense surveys will yield precision imaging of magma chambers underneath volcanos and earthquake rupture zones along faults.